GPS Jam, created by John Wiseman, is an online map of GPS interference, updated daily, based on GPS accuracy information reported by aircraft. It’s not necessarily a map of where GPS is being deliberately jammed, but when you look and see that the hotspots are the eastern Mediterranean, western Russia and the Baltics, well. Active war zones (e.g. Ukraine) are blank: this map is based on civilian aircraft data and those are no-go areas.